This invention relates in general to lock cylinders and deals more particularly with improvements in lock cylinders of the type which include a key plug stop for limiting rotation of a key plug relative to a cylinder shell.
A lock cylinder of the aforedescribed character is commonly used to operate an associated locking mechanism which may be actuated by less than one full rotation of a key. Such a lock cylinder may, for example, have a key plug arranged for 90.degree. or 180.degree. rotation between a shed or key withdrawal position and a lock operating position. Heretofore, various stop mechanisms have been provided for limiting rotation of a key -- key plug combination in such lock cylinders. One common form of stop comprises a pin which is mounted in fixed position on the cylinder shell and which projects into the shell bore between and in the path of a pair of angularly spaced abutment surfaces on the key plug. Another common form of stop includes an operating cam mounted in fixed position on the inner end of the key plug and arranged for rotation between fixed abutments associated with the inner end of the cylinder shell. While such key plug stops are generally satisfactory, one or more lock cylinder parts which comprise a stop mechanism usually must be handed to provide limited key plug rotation in a selected operating direction. Thus, the lock manufacturer may be required to maintain inventory of right and left-handed parts to facilitate assembly of lock cylinders for either clockwise of counterclockwise operation, as necessary for operation of various locking mechanism with which the lock cylinder may be used. Further, it may be necessary for the manufacturer to furnish each lock cylinder in a variety of axial lengths to satisfy various mounting requirements, all of which tends to further increase the parts inventory which must be maintained to enable assembly of locks to satisfy specific mounting and operating requirements.
Accordingly, it is the general aim of the present invention to provide an improved low cost stop mechanism which utilizes non-handed parts and which may be assembled as required to provide limited key plug rotation in either clockwise or counterclockwise direction.